Electric baseboard heat storage unit



Dec. 20, 1966 c. D. SNELLING 3,293,409

ELECTRIC BASEBOARD HEAT STORAGE UNIT Original Filed Oct. 21, 1964 5Sheets-Sheet 1 AIR FLOW G [I l8 l2 l7 l3 HEAT STORAGE MATERIAL /9 /l9 l92 f H 5 2 5 40 F! G. 2 K k HEAT STORAGE MATERIAL Liz?) INVENTOR.

.6 CHARLES D. SNELLING ATTORNEYS Dec. 20, 1966 Original Filed Oct. 21,1964 T E MPER AT U R E c. D. SNELLING 3,293,409

ELECTRIC BASEBOARD HEAT STORAGE UNIT 3 Sheeps-Sheet 2 FIG.6

- HE AT STORAGE MATERIAL T l M E INVENTOR; CH A RLES D SNELLING BY WATTORNEYS 1966 c. D. SNELLlNG ELECTRIC BASEBOARD HEAT STORAGE UNIT 5Sheets-Sheet 3 Original Filed Oct. 21, 1964 INVENTOR. CHARLES D- SNELLWGATTORNEYS.

United States Patent 3,293,409 ELECTRIC BASEBOARD HEAT STORAGE UNITCharles D. Snelling, 2949 Greenleaf St., Allentown, Pa. 18104 Originalapplication Oct. 21, 1964, Ser. No. 405,489. Divided and thisapplication May 12, 1966, Ser. No.

2 Claims. (Cl. 219-378) This application is a division of my US.application Serial No. 405,489, filed October 21, 1964 which applicationis a continuation-in-part of my application Serial No. 320,310, filedOctober 31, 1963, now abandoned.

The present invention relates to a baseboard heating unit and, inparticular, to a baseboard electric heating unit capable of maintaininga substantially more uniform flow of heat than prior heaters to an areabeing heated with minimum temperature fluctuation.

The use of electrical energy as a source of heat in the home has led tothe development of small compact baseboard units, so called because theyare adapted to be mounted against the baseboard of a wall of a room tobe heated. Like the baseboard, the unit is longitudinally configuratedexcept that it is hollow and has enclosed therein a longitudinallyarranged electric heating element which is connected into an electriccircuit in the usual conventional manner. Baseboard heaters aregenerally automatic and are operated by a thermostat strategicallylocated in a room or other area being heated. Such heaters may be 6inches high, about 2% inches deep and 2 to 3 feet long, or as long as 8feet, or even possibly longer. The heating element may comprise theusual 80 nickel-20 chromium electrical heat resistance elementcompletely enclosed within a metal sheath, e.g., a tube, the heatingelement being buried in an insulating material, such as powderedmagnesia or the like, for example similar to a Calrod unit.

Generally, heat exchanger fins surround the heating elements in order toassure optimum heat transfer efficiency, especially in the case wherethe baseboard heating unit works on the convection principle. Theheating is effected by either one of two ways: by the flow of airthrough the bottom opening of a grill, around the finned heating elementand then through the top opening of the grill work out into the room; orby heat reflection off a reflecting unit mounted inside the baseboardunit on the back side thereof behind the heating element. The convectiontype appears to be the more popular one in use today.

As stated above, the baseboard units are generally automaticallycontrolled by means of a thermostat. Because the elements are notcapable of maintaining or storing a high heat content, they are usuallydesigned to throw off a relatively high amount of heat in a short timeperiod. Thus, when the thermostat operates to shut off the electricpower, the heating unit immediately cools down and gives off no moreheat until the temperature in the room drops to a value corresponding tothe setting on the thermostat which actuates the power supply. Becauseof the time lag which is generally inherent in such a system, atemperature variation is usually noticeable in the room. It would bedesirable to have a unit that would not cool down rapidly and that wouldcontinually furnish some heat, even when the power is off, so as tosmooth out the temperature fluctuation and provides a more uniformheating.

I have now developed a heating unit which will overcome the foregoingdifficulties and provide a more uniform type of heating.

It is accordingly the object of my invention to provide a baseboardheating unit which is designed to store heat ice during a heating cycleand release heat during the off cycle.

Another object is to provide a baseboard heating unit having a heatstorage element in cooperable association with an electric heatingelement adapted to retain heat for release during an off cycle.

These and other objects will more clearly appear when taken inconjunction with the following description and the accompanying drawing,wherein:

FIG. 1 shows in front view a portion of a baseboard heating unit of anair convection type;

FIGS. 2 and 3 are transverse views taken along the lines 2-2 and 3-3,respectively, of FIG. 1;

FIG. 4 is illustrative of one embodiment of a heating element for usewith a baseboard of the type shown in FIGS. 1 to 3;

FIGS. 5 and 6 illustrate another embodiment of a baseboard heating unitof the heat-reflective type incorporating the novel features of myinvention;

FIG. 6A is a cross section taken along line 6A6A of FIG. 6;

FIG. 7 depicts temperature curves showing the kind of temperaturecontrol obtainable at the air outlet of the baseboard heating units ofmy invention as compared to the temperature control obtained by the moreconventional unit;

FIGS. 8 and 9 show a still further embodiment of a heating unit for usewith a baseboard of the type shown in FIGS. 1 to 3;

FIGS. 10 and 11 depict one type of heating element employed in theheating unit of FIG. 8, and

FIG. 12 shows in partial cross section an end view of a baseboard heaterillustrating the mounting employed in supporting the heating unit ofFIG. 8.

Stating it broadly, my invention comprises a baseboard heat storage andheat releasing unit comprising an elongated housing having a grill onthe front side thereof, and an electric resistance heater supportablydisposed within and along said housing with an elongated heat storagemodular element disposed in heat absorbing relation with the electricheater. The modular element is formed of a hollow longitudinal memberhaving encapsulated therein a chemical heat storage materialcharacterized by a relatively high heat of transition. By heat oftransition is meant the heat energy exchange which occurs when achemical heat storage material undergoes a phase change, for example, acrystallographic change in the solid state, or a change of state goingfrom the liquid phase to a solid phase, or vice versa.

Any one of a variety of heat storage materials may be employed incarrying out my invention. A material I may employ is anhydrous sodiumsulfate which has a transition temperature of about 450 F. and a heat oftransition in the solid state from one crystal form to another of about128 B.t.u.s per pound. Another is anhydrous sodium molybdate which has atransition temperature of about 820 F. and a heat of transition in thesolid state from one crystal form to another of about 128 B.t.u.s perpound.

An example of a material having a heat of transition based on a liquidto solid phase change is trisodium phosphate dodecahydrate (Na PO .12HO). The foregoing material has a latent heat of fusion or phase changeof approximately B.t.u.s per pound available for heat transfer at amelting temperature between to 180 F., provided there are no variationsin its crystallization as it gives up its latent heat. A particularlyuseful composition is one comprising 31 to 34% trisodiumphosphate, about4 to 7% sodium hydroxide and the balance water which has a melting pointof about '155 F. When the solid material is heated to F., it dissolvesin its own water of crystallization and when it is cooled to just below155 F. it crystallizes or solidifies and gives off an amount of heatcorresponding to about 100 B.t.u.s per pound. Examples of other heatstorage materials are lead acetate [(PbC H O .3H O] which melts at 167F., Na S O .5I-I O which melts at 120 F. and exhibits a latent heat oftransition of about 86 B.t.u.s per pound, NaCH COO3H O which melts at137 F. and exhibits a latent heat of transition of about 144 B.t.u.s perpound, and others.

I desire to use anhydrous sodium sulfate because in the solid state itis capable of storing heat over the range of 300 F. to 600 F. assensible heat and energy of phase change, that is energy of crystaltransition. working with materials in the solid state minimizescorrosion and containment problems.

By having a heat storage modular element disposed in heat absorbingrelation with the primary heating element, some of the heat is stored asheat of transition, such that when the primary heating element is shutoff by the thermostat, the baseboard heater cools slowly rather thanrapidly as heretofore. The heat storage element, having a high heatcontent, gives off its sensible heat until the temperature reaches thepoint at which the phase change of the contained heat storage materialoccurs after which it gives up its heat of transition. Instead ofobtaining a rapid fluctuation of the temperature during the off cycle, asort of temperature modulation results as illustrated in FIG. 7 whichdepicts qualitatively the fluctuation of temperature with time of airleaving the outlet of a thermostatically controlled heater. Two curvesare shown, one where the baseboard heater does not contain a heatstorage element (curve A) and the other (curve B) where the baseboardheater contains a heat storage element. It will be noted that a broaderband of temperature fluctuation is indicated (curve A) with a baseboardheater outside the invention as compared to a more modulated temperaturevariation (curve B) indicated with the baseboard heater or assembly ofthe invention.

Referring now to FIGS. 1 to 3, I show a portion of a convection typebaseboard heater comprising an elongated housing designated generally bythe numeral 1 having a back side 2 for mounting against the base of awall, top and bottom flanges 3 and 4, respectively, integral with theback side and a grill 5 on the front side thereof, said grill definingtop and bottom openings 6 and 7, respectively, which cooperate withother elements within the housing to provide a convective flue for airflow into and out of the baseboard heater as shown in FIG. 3.

Referring to FIG. 3, which is a transverse section taken along line 3-3of FIG. 1, bottom flange 4 is shown integral with back side 2, theflange terminating into a bent portion 8 which extends inwardly of saidhousing to provide a convection path rearwardly of a partition 9 whichis configurated as an inverted L section extending longitudinally ofsaid housing between the back side thereof and grill 5.

Grill 5, forming the front face of the baseboard heater shown in FIG. 3,comprises two spaced apart elements 5a and 5b whereby to provide a pathfor the flow of air therebetween to keep the front grill portion fromoverheating. In this embodiment of the invention, the electricalresistance heating element and the heat storage modular element areformed into the heat assembly shown generally by the numeral 10 (noteFIGS. 2, 3 and 4) wherein the modular element 11 is held adjacent to andin heat absorbing relation with heating element 12 by means of heatexchanger fins 13' of aluminum of other heat conductive metal. Theheating element comprises a metal sheath which has within it anelectrical resistance element '14 which is insulated from the sheath bya powdered refractory =15 such as magnesia and is connected byconventional means (not shown) to a source of power. The heating elementand Moreover,

heat storage modular assembly is supported within the housing at the endwalls, for example, at end wall .16 via U-shaped saddles 17 and 18,respectively, which extend inwardly from the end wall as shown inFIG. 1. The modular element embodiment shown in FIGS. 2 to 4 comp-risesa hollow member having a rectangular cross section and havingencapsulated therein a heat storage material 19, such as anhydroussodium sulfate. It is desirable that the material of construction becorrosion resistant to the wide variety of the contained heat storagematerials which may be employed. Such construction materials maycomprise stainless steel, nickel, the nickel alloy known by thetrademark Inconel or other suitable material of construction. Preferablythe modular element shown in FIGS. 1 to 4 should have a dark surface soas to absorb heat efliciently from the heating element. Where a metalsheath is used for the modular element, the surface should preferablyhave a black oxide coating to insure efiicient heat absorption from theheating element. As stated hereinabove, b aseboard heaters are usuallycontrolled by a thermostat which is not shown in the drawing since itsuse in combination with electric heaters is well known to those skilledin the art.

The convection flow of air into and out of the housing of the heater isillustrated in FIG. 3 which shows the main flow of air as depicted bythe broad arrows as going around the fins of the heating element and theheat storage modular element. Minor fl-ow paths of the air are alsoshown, one between elements 5a and 5b and the other rearwardly ofpartition 9. The minor flow path of air keeps the front and back side ofthe baseboard from overheating while at the same time conducts some heatfrom the heater into the room, while the major flow of air about theheat exchanger fins 13 removes a good portion of the heat beinggenerated.

My invention as applied to another baseboard heater of theheat-reflective type is shown in FIGS. 5 and 6 as also comprising anelongated housing designated generally by the numeral 20 comprising backside 21 adapted to be secured to and along the base of a wall and anopen or foraminous grill 22. The grill is formed of slender elements 23of stainless steel, aluminum or other suitable material runninglongitudinally of said housing and slender transverse elements 24running across the face of the grill and abuttingly assured to elements23 at their points of contact by resistance welding or other suitablemeans. The grill face is adapted to be spring fitted to the back side ofthe housing as shown in FIG. 5 at 25 and 26, respectively.

Attached to the back side within the housing is a longitudinal reflectorplate 27 of polished metal, such as sheet aluminum or chromium platedsheet metal. Suspended forwardly of said reflector and behind the grillis an electric resistance heating unit 28 supported by insulated means29 projecting from the top and bottom of the housing and along thereof,the opposite ends of the electric heating resistant unit being adaptedfor connection (not shown) toa source of power. As in the firstembodiment, a heat storage modular element 30 is provided between thereflector 27 and the heating unit 28, the modular element beingsupported by means projecting from an end wall 31 of the-housing. Thesupporting means may comprise a saddle 32 (shown hebind the end wallflange 33, in FIG. 6) formed as a U-s-hape as shown more clearly in FIG.6A.

The heat storage material 34 encapsulated in the modular element may bethe same as that used in the embodiment shown in FIGS. 1 to 4. As in thefirst embodiment, the thermostatically controlled electric heatresistance unit throws off heat which, in this case, is reflected intothe room being heated. Some of the heat is absorbed by the heat storagemodular element and stored as latent heat of transition which it givesoff during the off cycle, thereby minimizing temperature fluctuation inthe room between the on and ofl heating cycle.

In FIGS. 8 to 12, I show as another embodiment a heating unit in whichthe heating element is encased within the heat storage modular elementto insure optimum heat absorption by the heat storage material. Theelongated modular element is substantially rectangular in cross section.The outside casing of the modular element is formed of an extrudedchannel 35 of aluminum having a pair of inwardly projecting shoulders36, 37 running longitudinally of the channel. Each of the shoulders islongitudinally grooved (38, 39) and receives therein a plate or sheet40' of aluminum therealong to complete the enclosure of the modularelement. Cooling fins 41 in the shape of a T project outwardly from thesurface of fitted plate along the whole length of the element. Themodular element is enclosed at its end 42 by a cap 43, the opposite endbeing similarly capped but being left exposed for purposes of clarity.The modular element is filled with a heat storage material 44, such asanhydrous sodium sulfate, and has embedded in it an electricalresistance heating element 45 which is encased in .a protective sheathof stainless steel 46 filled with an insulating material, such asmagnesia, which completely surrounds the heating element. The wholeelement, including the sheath, is bent into a U shape as shown (inphantom) in FIG. 8 and as shown in FIG. 10. The ends of the electricalresistant element are connected to terminals 47, 48 which in turn areconnected to power lines, not shown.

The electrical heat resistance elements are preferably assembled asshown in FIG. 10. The loop of the element at 49 is reinforced by meansof a bracket 50 using sheet metal which is formed-fitted about the loop.Vanes 51 are provided comprising sheet metal aluminum or other suitablemetal of high thermal conductivity with the sides cylindrically formedfor slipping over the legs of the heating element as shown in FIG. (notealso FIG. 11). A pair of guide members 52, 53 are riveted to the back ofthe vanes via rivet-s 54. The purpose of the guides is to help positionthe electrical resistance heating element within the modular heatstorage element. In mounting the modular element 35 Within the baseboardheater of the type shown in FIGS. 1 to 3, a C-shaped hanger 55 isemployed which connects via an over hang 58 to a bracket mount 56attached to the back of the rear wall 57 of the baseboard heater asshown in FIG. 12. The C-shaped hanger is configurated to receive andsupport the modular heat storage element and projecting fins 41 in backof grill or front face 5 as depicted in FIG. 12.

It is apparent from the foregoing that I provide a novel baseboardheating element which overcomes the disadvantages of the conventionalheaters by providing more uni- 'form heating while minimizingtemperature fluctuations between heating cycles in the immediate areabeing heated.

In effect, my novel baseboard heating element operates as a modulatingand temperature averaging device, that is, with my device there is lessthermal variation at the heater when the power is off as compared to theconventional baseboard heater, even though the baseboard heater operatesat a slower initial warm-up. However, the slower warm-up is advantageousas it inhibits overshoot of temperature (note FIG. 7). For example, inthe spring, the air flowing out of the baseboard heater may range intemperature from to F. with the conventional baseboard heater, thedevice cools rapidly the moment the power is shut off, whereas, with mydevice, because of its high heat content, heat is continuously beingdelivered on the off-cycle while the room is losing heat. In the dead ofwinter when the temperature of the air leaving the baseboard ranges fromto R, my device maintains a balance of heat output during the off cycle,while with the conventional baseboard heater the temperature of the airleaving the heater falls markedly the moment the power is shut ofithermostatically. This non-continuous type of heating results in markedtemperature variations within a room leading in many instances todiscomfort.

Although the present invention has been described in conjunction withpreferred embodiments, it is to be understood that modifications andvariations may be resorted to without departing from the spirit andscope of the invention, as those skilled in the art will readilyunderstand. Such modifications and variations are considered to beWithin the purview and scope of the invention and appended claims.

What is claimed is:

1. A baseboard heat storage and heat releasing unit comprising anelongated housing having a back side for mounting against the base of awall and an open front, a foraminous grill covering the fnont side ofsaid housing, a heat reflector connected to the back side of saidhousing having a polished surface and being shaped for reflectingsubstantially all the heat outwardly thereof through said grill, anelectric resistance heater supportably disposed within and along saidhousing in spaced relation to an elongated heat storage modular elementsupportably disposed in heat absorbing relationship with said electricresistance heater, said heater and said heat storage modular elementbeing positioned between the heat reflector and said grill, said grill,reflector, heater and heat storage modular element extendingsubstantially the length of the housing, said modular element beingformed of a hollow longitudinal container having encapsulated therein achemical heat storage material characterized by a relatively high heatof transition.

2. The baseboard heater of claim 1, wherein the heater is positionedbetween the grill and the reflector, and the heat storage modularelement is spaced between the reflector and the heater.

References Cited by the Examiner UNITED STATES PATENTS 1,706,846 3/ 1929Fisher. 2,066,127 12/1936 Slayter 2l9341 2,677,664 5/ 1954 Telkes.3,223,827 12/1965 Welch 219368 X FOREIGN PATENTS 636,942 5/1950 GreatBritain.

ANTHONY BARTIS, Primary Examiner.

1. A BASEBOARD HEAT STORAGE AND HEAT RELEASING UNIT COMPRISING ANELONGATED HOUSING HAVING A BACK SIDE FOR MOUNTING AGAINST THE BASE OF AWALL AND AN OPEN FRONT, A FORAMINOUS GRILL COVERING THE FRONT SIDE OFSAID HOUSING, A HEAT REFLECTOR CONNECTED TO THE BACK SIDE OF SAIDHOUSING HAVING A POLISHED SURFACE AND BEING SHAPED FOR REFLECTINGSUBSTANTIALLY ALL THE HEAT OUTWARDLY THEREOF THROUGH SAID GRILL, ANELECTRIC RESISTANCE HEATER SUPPORTABLY DISPOSED WITHIN AND ALONG SAIDHOUSING IN SPACED RELATION TO AN ELONGATED HEAT STORAGE MODULAR ELEMENTSUPPORTABLY DISPOSED IN HEAT ABSORBING RELATIONSHIP WITH SAID ELECTRICRESISTANCE HEATER, SAID HEATER AND SAID HEAT STORAGE MODULAR ELEMENTBEING POSITIONED BETWEEN THE HEAT REFLECTOR AND SAID GRILL, SAID GRILL,REFLECTOR, HEATER AND HEAT STORAGE MODULAR ELEMENT EXTENDINGSUBSTANTIALLY THE LENGTH OF THE HOUSING, SAID MODULAR ELEMENT BEINGFORMED OF A HOLLOW LONGITUDINAL CONTAINER HAVING ENCAPSULATED THEREIN ACHEMICAL HEAT STORAGE MATERIAL CHARACTERIZED BY A RELATIVELY HIGH HEATOF TRANSITION.